1. Field of the Invention
The present invention relates to a driving circuit and a driving method for driving scanning lines or image signal lines of a display panel.
2. Description of the Background Art
For example, in liquid crystal display devices, a driving circuit (scanning line driving circuit) for driving scanning lines of a display panel (a liquid crystal panel) is configured so as to output signals whose number corresponds to the number of the scanning lines of the liquid crystal display panel. Similarly, a driving circuit (image signal line driving circuit) for driving image signal lines of the liquid crystal display panel is configured so as to output signals whose number corresponds to the number of the image signal lines.
In general, since the number of scanning lines and the number of image signal lines in the display panel are larger than the number of signals (the number of the output terminals) that can be outputted by one driving circuit (integrated circuit), the scanning lines and the image signal lines are driven by using a plurality of driving circuits that are cascade-connected. From a viewpoint of reduction in the cost of liquid crystal display devices, since it is preferable that the number of driving circuits to be used is smaller, the number of output terminals provided in one driving circuit tends to increase according to recent improvement of fine processing technology.
It is the most efficient that all the output terminals in a driving circuit are used. However, since resolution (the numbers of scanning lines and image signal lines) of the display panel varies, the number of required signals does not always match with the number of the output terminals in the driving circuit. Recently, since the number of the output terminals in the driving circuit increases, it is more difficult than ever to adjust the resolution of the display panel to the number of the output terminals in the driving circuit. For this reason, some output terminals of the driving circuit are not often used.
A driving circuit having a function for enabling the number of output terminals to be switched (namely, some of them can be disabled to be used) according to standard resolution of the display panel is also proposed (for example, Japanese Patent Application Laid-Open No. 2009-128776).